rs63750555

Variant names:

• chr3-36993616-A-C
• NM_000249.4:c.69A>C

Your query was ambiguous. Multiple possible variants found:

• chr3-36993616-A-C
• chr3-36993616-A-G
• chr3-36993616-A-T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM2 PM5 PP3_Strong PP5_Moderate

The NM_000249.4(MLH1):​c.69A>C​(p.Glu23Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Benign in Lovd. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. E23K) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 1.17

Genes affected

MLH1 (HGNC:7127): (mutL homolog 1) The protein encoded by this gene can heterodimerize with mismatch repair endonuclease PMS2 to form MutL alpha, part of the DNA mismatch repair system. When MutL alpha is bound by MutS beta and some accessory proteins, the PMS2 subunit of MutL alpha introduces a single-strand break near DNA mismatches, providing an entry point for exonuclease degradation. The encoded protein is also involved in DNA damage signaling and can heterodimerize with DNA mismatch repair protein MLH3 to form MutL gamma, which is involved in meiosis. This gene was identified as a locus frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). [provided by RefSeq, Aug 2017]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-36993614-G-A is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.976
• PP5: Variant 3-36993616-A-C is Pathogenic according to our data. Variant chr3-36993616-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2586631.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.69A>C	p.Glu23Asp	missense_variant	Exon 1 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.69A>C	p.Glu23Asp	missense_variant	Exon 1 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:1

Sep 08, 2023

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.E23D variant (also known as c.69A>C), located in coding exon 1 of the MLH1 gene, results from an A to C substitution at nucleotide position 69. The glutamic acid at codon 23 is replaced by aspartic acid, an amino acid with highly similar properties. A functional study showed only 25% mismatch repair activity in yeast with the p.E23D variant; however, protein expression studies indicated >75% expression relative to wild type MLH1 (Takahashi M et al. Cancer Res, 2007 May;67:4595-604; Abildgaard AB et al. Elife, 2019 Nov;8). These findings suggest that loss of MLH1 expression may not be detected by immunohistochemistry (IHC) in those with p.E23D. In another functional study, this variant (p.E20D in yeast) demonstrated a mutator phenotype in a yeast reversion assay (Wanat JJ et al. Hum. Mol. Genet. 2007 Feb;16:445-52). Furthermore, an alteration resulting in the same protein change, c.69A>T, has been identified in at least one proband who met Amsterdam I/II criteria for Lynch syndrome and a second proband whose Lynch syndrome-associated tumor demonstrated loss of PMS2 expression by IHC (Ambry internal data). Based on internal structural analysis, E23D is tolerated. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.41
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D
Eigen	Benign	-0.13
Eigen_PC	Benign	-0.15
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.66	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Uncertain	0.059	D
MutationAssessor	Pathogenic	4.2	H
PrimateAI	Pathogenic	0.80	T
PROVEAN	Benign	-2.3	N
REVEL	Pathogenic	0.85
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.016	D
Polyphen		1.0	D
Vest4		0.81
MutPred		0.88		Loss of helix (P = 0.1706);
MVP		0.99
MPC		0.36
ClinPred		1.0	D
GERP RS		2.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6
Varity_R		0.96
gMVP		0.80

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr3-37035107;